Underswap: The Purple Soul of William Gaster
by Dawn Totadile
Summary: The third installment in the Soul Series, this goes into the Underswap-verse, so you know what that means, time to mess with W.D. Gaster instead, eh? Don't worry, same idea and all that, but Swap Gaster isn't exactly an opposite of himself, nor is he exactly like normal Arial, but he's pretty close. ;P Enjoy, and the next story will come soon.
1. Chapter 1

People had been known to disappear around the top of Mt. Ebbot. One such person was a young man named William Dingus Gaster. He was a young scientist that had recently graduated from college with a masters in engineering and mechanics. Very few knew that he was a descendent of three of the seven sages that had sealed monsters in the underground over a thousand years ago, or that he had been descended from two of the sages that had actually been friendly towards monsters. The only reason that the red soul, the light blue soul, and the purple soul had even considered sealing the monsters was to protect them from the rest of the humans, and with the blessings of the Queen, they did what they had to do to help protect their friends and the kingdom they lived in.

The stories behind the monster imprisonment had been a long standing tradition to pass down from the Gaster and Mincho family. The Gasters were descended from the Dark Blue Soul of Integrity while the Mincho family was from the purple soul of perseverance and the light blue soul of Patience.

William had always been a strange man, preferring to spend his time in a lab or a library. He was about seven feet tall, with dark brown hair and bright blue eyes that darkened or turned purple when he attempted to use the ancient sage magic in his soul. He wore a set of cloudy glasses and had a backpack full of multiple journals and other things he would be able to use after descending down to the underground. He was a cheerful fellow with a light hearted sense of humor and a love for riddles, but if one was foolish enough to get him angry, they'd find he was well able to defend himself.

He gave one last look to the rising sun that had seemed to be chasing him. He grinned ruefully, knowing that he would probably never see the light of day again, and yet… somewhere in his soul he felt that he might, should the cards be played right. He shrugged and climbed down into the cave using a rope that had an end tied to one of the rocks.

As he landed in a pile of buttercups, he noticed the rope fall after him. He rolled his eyes and smirked. He loved magic, and the idea of magic mixing with science was always one that had fascinated him. He packed up the rope into his bag again and looked around. He seemed to be in some sort of ruins, no doubt the original home area for the monsters after being banished underground. He sighed as he pulled out his soul. It was purple, damaged, and sickly, but it was still filled with perseverance. He would persevere through the trials ahead of him until his brain tumor finally killed him.

As he entered the next room, he found himself looking at a strange cat like creature that was sending so many alarms through his head at the moment. "Hoi, I'm TemMie! TemMie the TeM! YOu nEw hErE? YOU mUst BE so coN-fU-sED! NO wORrY! TeMmie SMarT! TemMie shOw yOU wAy of LIfe hErE!"

William flinched as he felt his soul tug. His bright blue eyes hardened into a dark blue glare. Something wasn't kosher. Whatever this thing was… it wasn't acting like it should have been. His soul was a rich royal purple that had some dark patches in it from his brain tumor's effect. The Temmie seemed confused for a moment before shaking it's head and continuing. William dodged every "Temmie Flake of Friendliness" that was shot at him, enraging the strange cat like creature.

"You done? I'm not up for gaining a level in violence just because you want to be a pill. I'm just here to help out."

"So YoU KnOw AbOUt ThE AcRoNyMs? YoU wOnT GeT FaR."

"Not planning on it. I only need to do one thing before I die and that's help out around here. By my estimation, my cancer will have me killed within the next year, so I think I should get to choose how I use my last year." William smirked dangerously as he summoned his own type of attack. It was a blaster of sorts that looked like a book. "This is a Gaster Blaster Prototype, do you want to test it, Temmie?"

The weird cat creature twitched before just running away yelling about how the human was crazy. William just chuckled and allowed the book to disappear after he shot a few healing words from it to himself.

"I'll never get tired of seeing that, bullies running away from items that are meant to heal, hehe." William made his way through the puzzles that guarded the ruins, sparing all that he came across. Eventually he made his way to a house that seemed to have a nice garden in front of it. Much to his surprise, a human and two monsters were in the garden. "Hello there?"

The human was an old lady, probably older than William's father by the looks of her, and she had a neat bun that was tied up with a blue ribbon and a knife in her hand which was used to cut the weeds. "Oh, hello there." She said in a kindly voice. "Did you fall down as well? I'm Jenna Stone of the Patience Clan, gardener of the ruins." She was slightly pale skinned with vibrant blue eyes that showed her to be young in spirit while her body was old for a human. "You better come in peace young man."

William smiled and nodded. "I'm Dr. William D. Gaster of the Perseverance, Patience, and Integrity Clans."

"A Gaster, eh? You wouldn't happen to be young Harrington's boy, would you?"

"Actually yes… he married Mary Sue Mincho…" William grimaced.

"Huh… okay, I guess I owe Stanley fifty G. I can't believe his brother got married…" The old lady laughed as she got up with the help of the blonde haired goat monster next to her. "Thanks, Pops."

"Heh, not a problem, my child." The goat monster looked rather young himself, probably because monsters aged slower. The goat monster looked to the young man with a smile. "Hello, Dr. Gaster. I am Asgore, keeper of the ruins and guardian of Home. I make sure that anyone who falls is safe to pass."

"Huh, must get pretty lonely here."

"Sometimes, but it hasn't been so bad since Jenna showed up. My wife occasionally comes by to see how I'm doing as well as my son, Asriel. I'm not really needed up at the capital and we like to know the kind of humans that fall down here." He then turned towards the other monster, a female skeleton with a clipboard in her hands and wearing a long white labcoat. "This is the royal scientist. She sometimes comes to visit as well. Dr. Serif, why not introduce yourself?"

The young lady skeleton jerked her head up, as though just noticing that another human had shown up. She blushed a sky blue in embarrassment. "Oh, um… hello… I'm Dr. Arial Serif." She held out a hand for the human to shake.

William looked her up and down before taking her hand in his, and gently leaning down to kiss it in a gentlemanly fashion. "Charmed, I'm Dr. W. D. Gaster."

"What's the D. stand for, William?" Jenna smirked as she saw both scientists blush.

William frowned. "Can we leave it at my father has a cruel sense of humor?"

"NOPE!" Jenna laughed out loud. "I'm your mother's cousin, I'm allowed to know what her boy got named."

"… Dingus…" William said with the straightest face ever.

The three others looked at him for a few good minutes before Jenna just broke down into laughter. "He would!"


	2. Chapter 2

Arial took William through the rest of the ruins while explaining everything she could about monster society and what had happened to the other humans who had fallen.

Jenna had been the only one to stay in the ruins, and she had been ten when she fell. Rumor had it that somewhere along the path to Snowdin there was a young boy who represented the soul of Bravery that had been frozen in the snow almost a thousand years ago and his soul was supposedly held in a container in the capitol. About a hundred years ago now, a young girl had shown up as the soul of kindness and became a famous chef. Her body was now in a hall in the royal palace where the dead humans were laid to rest, and her soul was in a container as well. A rumor had said that her body had reverted to her teenage form that she had fallen in with when she died. Jenna herself was so close to death that Asgore was certain that the next time his wife and son came over he would have to give her soul to them. A middle-aged man who was the soul of Integrity was raising a young rambunctious yellow dinosaur girl in the Hotlands area. He had fallen down around eighteen and had stayed around, teaching piano to monsters who wanted to learn, as well as how to fight.

The original human to fall had been Princess Frisk who had been adopted by the royal family, along with an armless lizard boy named Miko that had the nickname "Monster Kid". Miko and Frisk had met an untimely death which had started the "Separation" of the royal family. Asgore had decided to tend to the gardens of the ruins and become the keeper, making sure to care for and warn any humans that came through about what to expect. Torial, the Queen of Monsters, kept on governing the kingdom and trying to not kill the humans out of revenge, as there were not enough anyway to break the barrier. Torial liked to bake pies for her people and would often get help from the staff who had worked under the soul of kindness to host fairs and festivals, trying to keep up hope for her people. Asgore and Jenna would bring flowers of all sorts to these events as well. The only biological child of Asgore and Torial was Asriel, and he was about the age of a teenager now in monster terms, though he still wore his favorite striped shirt. He tended to bounce around from century to century on which parent he would stay with. This century, he was staying with his mother, learning how to rule the kingdom.

Arial learned quite a bit about William as they made their way to Snowdin, where Arial had a house and where a nice inn was for William to stay at. She learned that he was half deaf and had to wear a hearing aid or use his hands for speech purposes. She also learned that he actually preferred to be called W. D. or Wing Dings rather than William. William in turned learned that Arial had lost her parents when she was very young, and had been the royal scientist since she was a teenager. Arial was also working with a young fish woman by the name of Undyne Fisher, as her assistant and protégé. They both hoped to learn more about each other though as they went along.


	3. Chapter 3

Wing had been working with Arial and Undyne in the labs for about a month now on Arial's greatest design, the Core; a creation to power everything from Home to New Home. The lab was in the middle of Waterfall, which was quite convenient for the fish monster who was the apprentice of Arial. William was busy filling out a calculation on a chalkboard when his stomach growled. He rolled his eyes and ignored it, but his female companions did not.

"Uh, Doc, you need to eat something." Undyne pointed out shyly. She was a young Fish woman of about 15 and a prodigal genius that was easily nervous and tended to make big mistakes under tons of pressure. While she was getting better at it, some of her biggest mistakes were in the labs below the trio.

"She's right, William. You need to eat something. You haven't eaten in quite a while." At this point, only Arial called him by his real name. Everyone else in the underground had taken to calling him Wing Dings, Doc, or just plain Gaster.

William sighed. If Arial was on his case then he would definitely have to eat something. "Very well… but only because you both are insisting. I'm fine, really."

"Doc., humans need more food in their system than monsters like me. Why don't we visit your uncle and cousin in Hotlands?" Undyne offered nervously.

William had found out rather quickly that his father's twin brother, Roman, had survived falling down there over twenty years ago during one of his father's fits, and had adopted a young monster by the name of Alphys. William also knew that Undyne had a cute little crush on the younger monster.

"How's about you go visit them and tell them I said 'Hello' while I head over to Snowdin for some of Muffet's baked goods. You know I love those Honey Muffins she makes. Not to mention some honey tea is always good for the mind."

Arial chuckled. "You just like honey, don't you?" William helped her to put her coat on.

"You got it, Honey." Arial blushed a bright sky blue as she quickly turned her head towards him. William just kept laughing at the scientist's shock. Undyne was already gushing on the two making an adorbs couple.


End file.
